Electroplating pretreatment wastewater treatment process

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to an electroplating pretreatment wastewater treatment process which comprises the following steps: step 1, storing floating oil in an oil collection area by using an oil removal tank, and continuously increasing the content of the floating oil on the liquid level of the oil collection area; 2, unemulsified floating oil in the oil collecting area is extracted; 3, pumping out the wastewater containing emulsified oil in the oil removal tank, and carrying out demulsification treatment; step 4, adding a pH regulator into the demulsified wastewater to reduce the pH value of the wastewater to 6-8; 5, stirring and separating after adding a flocculating agent to obtain a treating fluid; and step 6, filtering the treatment liquid to obtain standard water, collecting unemulsified floating oil, and demulsifying the waste liquid containing emulsified oil to reduce the use amount of a demulsifier and a flocculant.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and specifically relates to a process for treating electroplating pretreatment wastewater. Background Art

[0002] Before electroplating, the workpiece must be cleaned of oil and dirt on its surface. Generally, it is immersed in a solution prepared with an active agent. The grease is emulsified and dispersed in the solution by the active agent. The alkaline degreaser in the solution and the emulsified oil droplets are mixed to form water-soluble fatty acids. Then, clean water is used to soak and wash away the solution attached to the surface of the workpiece.

[0003] When using surfactants for cleaning, excessive addition of surfactants to the solution may cause the surfactant to precipitate on the surface of the solution, or the solution may be used for a long time and oil may appear on the surface, which may adhere to the surface of the workpiece when it is taken out. In general, unused ingredients such as degreasers and emulsifiers may appear on the surface of the solution.

[0004] The existing technology often uses steel belt skimming or floating suction devices to directly remove the floating oil on the surface of the solution, but this may cause the components used to remove grease, such as the precipitated active agent, to be removed as well.

[0005] In addition, when demulsifying the wastewater after deoiling, the unemulsified dispersed oil in the wastewater will compete with the emulsified oil for the demulsifier, resulting in the need to use more demulsifier when treating more saturated wastewater. Summary of the Invention

[0006] The object of the present invention is to provide a process for treating electroplating pretreatment wastewater, which can remove floating oil in advance and reduce the use of subsequent demulsifiers and flocculants.

[0007] The present invention proposes a process for treating electroplating pretreatment wastewater, which is characterized by comprising the following steps: Step 1: Use a degreasing tank to store the floating oil in the oil collection area, and allow the floating oil content on the liquid surface of the oil collection area to continue to increase; Step 2: Extract the unemulsified floating oil from the oil collection area; Step 3: Extract the wastewater containing emulsified oil from the degreasing tank and perform demulsification treatment; Step 4: Add pH regulator to the wastewater after demulsification to reduce the pH value of the wastewater to 6-8; Step 5: Add flocculant, stir and separate to obtain treated liquid; Step 6: Filter the treated liquid to obtain qualified water.

[0008] Furthermore, the oil removal tank includes an oil removal area and an oil collection area, the liquid levels of the oil removal area and the oil collection area are not interconnected, and the liquid level of the oil removal area is continuously input into the oil collection area.

[0009] Furthermore, step 1 and step 2 are carried out in a deoiled state.

[0010] Furthermore, in step 1, the unemulsified dispersed oil in the solution is floated by air flotation.

[0011] Furthermore, in step six, when filtering the treated liquid, it is first filtered through an ultrafiltration membrane and then filtered through a reverse osmosis membrane.

[0012] The oil removal tank used in the above wastewater treatment process includes multiple floating oil removers that continuously input the liquid level in the oil removal area into the oil collection area. The floating oil removers are connected by a square frame. A bracket is provided on the square frame. The bracket moves with the floating oil removers and causes the second hose on the bracket to move up and down with the floating oil removers.

[0013] Furthermore, the relative height of the liquid inlet of the second hose is greater than the relative height of the liquid inlet of the floating oil remover.

[0014] The beneficial effects achieved by the present invention using the above structure are as follows: (1) Only the liquid surface in the degreasing area of ​​the workpiece is processed to reduce the area of ​​the degreasing liquid surface, improve the accuracy of removing floating oil, and improve the degreasing efficiency; (2) The components removed from the degreasing area are still present in the degreasing tank, and the active agent removed by the floating degreasing device can still be reused; (3) First collect the unemulsified floating oil, then demulsify the waste liquid containing emulsified oil to reduce the use of demulsifiers and flocculants; (4) Continuously accumulate the floating oil in the degreasing tank to increase the thickness of the unemulsified grease layer, making it easier to collect the unemulsified grease; (5) Taking advantage of the fact that the density of oil is lower than that of water, a bracket that floats with the floating oil remover is set to support the second hose at a position higher than the floating oil remover, thereby realizing a floating oil collection method that is adaptive to the liquid level height; BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the oil removal device of the present invention; Figure 2 Schematic diagram of the partition structure of the present invention; Figure 3 This is a schematic diagram of the oil removal state of the present invention; Figure 4 It is the liquid level state diagram of the degreasing tank of the present invention; Figure 5 This is a schematic diagram of the wastewater treatment structure of the present invention; Figure 6 This is a schematic diagram of the oil floating suction structure of the present invention; Among them, 1. Oil removal tank; 2. Liquid level separation equipment; 201. Delivery pipeline; 202. First hose; 203. Gate; 204. Gate; 205. Sealing part; 206. Connecting part; 207. Sealing protrusion; 208. Cylinder; 3. Floating oil remover; 4. Lifting device; 5. Gantry; 6. Electroplating drum; 7. Flotation unit; 8. Square frame; 9. Second hose; 10. Bracket.

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present invention.

[0019] Example 1

[0020] like Figures 1 to 4 As shown, an electroplating workpiece degreasing device used in the present invention includes a degreasing tank 1, a liquid level separation device 2, and a floating degreasing device 3.

[0021] The liquid level separation device 2 is located inside the oil removal tank 1. The liquid level separation device 2 divides the liquid level in the oil removal tank 1 into an oil removal area and an oil collection area, so that the liquid levels in the oil removal area and the oil collection area are not interconnected, and the floating oil in the oil collection area cannot spread to the oil removal area through the liquid surface.

[0022] The floating oil remover 3 is located in the oil removal area of ​​the oil removal tank 1. The floating oil remover 3 floats on the liquid surface of the oil removal area to collect floating oil in the oil removal area.

[0023] A conveying pipe 201 is also provided on the liquid level separation device 2. The conveying pipe 201 is located below the liquid level near the bottom of the deoiling tank 1. One end of the conveying pipe 201 is located below the deoiling area, and the other end of the conveying pipe 201 is located below the oil collecting area. The liquid in the deoiling area can be transported to the oil collecting area through the conveying pipe 201.

[0024] The conveying pipeline 201 and the floating oil skimmer 3 are connected by a first hose 202. After the floating oil skimmer 3 collects the floating oil in the oil removal area, it is transported to the conveying pipeline 201 through the first hose 202, and then the floating oil is transported from the oil removal area to the oil collection area through the conveying pipeline 201.

[0025] After the floating oil enters the oil collection area from the oil removal area, it first enters below the liquid surface of the oil collection area. Because the specific gravity of the floating oil is smaller than that of water, the floating oil will float from below the liquid surface and gather on the surface of the oil collection area.

[0026] When the floating oil remover 3 is exposed to oil floating, it will not only collect the floating oil, but also collect the precipitated active agent / emulsifier and part of the liquid containing the active agent / emulsifier, and send them to the bottom of the liquid surface through the delivery pipe 201, so that the precipitated active agent / emulsifier and part of the liquid containing the active agent / emulsifier can be remixed with the medicine.

[0027] The portion of the liquid level separation device 2 located below the liquid level is further provided with a gate 203 connecting the oil removal area and the oil collection area, and is also provided with a gate 204.

[0028] like Figure 3 、 4 As shown, the gate 204 is divided into two parts, namely the blocking part 205 and the connecting part 206. When the gate 204 moves downward, the blocking part 205 gradually overlaps with the gate 203. At this time, the water area of ​​the oil removal area and the oil collection area are completely separated.

[0029] After the oil removal area and the oil collection area are separated, in the absence of external interference, the liquid collected in the floating oil skimmer 3 is always stored in the first hose 202 because the pressure on both sides of the outlet of the delivery pipe 201, that is, its end located in the oil collection area, is the same; like Figure 1 and Figure 3 As shown, the lifting device 4 carries the electroplating drum 6 and moves along the gantry 5 to the top of the degreasing tank 1. At this time, the blocking part 205 and the gate 203 are in an overlapping state, the lifting device 4 descends, and the electroplating drum 6 is sent to roll into the degreasing tank 1. After the electroplating drum 6 is immersed in the degreasing area, the liquid level in the degreasing area rises. As the liquid level rises, the floating oil remover 3 drives the liquid height in the first hose 202 to rise, causing the pressure balance at the outlet of the delivery pipeline 201 to be broken, and the liquid in the first hose 202 begins to enter the oil collection area.

[0030] At the same time, part of the oil on the surface of the workpiece floats to the liquid surface of the degreasing area to form floating oil. The floating oil and part of the degreasing solution are collected by the floating degreasing device 3 and sent to the oil collection area through the first hose 202. After entering the oil collection area, the degreasing solution is mixed with the solution in the oil collection area again, and the floating oil floats to above the liquid surface of the oil collection area.

[0031] There are two sealing protrusions 207 on the blocking portion 205. When the gate 204 moves downward, the lower sealing protrusion 207 forms a seal with the lower part of the gate 203. When the gate 204 moves upward, the upper sealing protrusion 207 forms a seal with the upper part of the gate 203.

[0032] When the workpiece is deoiled, the cylinder 208 is retracted, the gate 204 moves upward, the connecting part 206 gradually overlaps with the gate 203, the deoiling area and the oil collecting area below the liquid level are connected again, the pressures in the deoiling area and the oil collecting area are synchronized again, the floating deoiler 3 stops collecting floating oil, the drum 6 is lifted by the lifting device 4 again, and the liquid levels in the deoiling area and the oil collecting area drop synchronously.

[0033] Example 2

[0034] like Figure 5 As shown, the present invention also provides a process for treating electroplating oily wastewater, comprising the following steps: Step 1: Use the degreasing tank in Example 1 to store the floating oil in the oil collection area, and continuously increase the floating oil content on the liquid surface of the oil collection area. At the same time, the degreasing solution in the oil collection area is floated by the flotation unit 7 to reduce the dispersed oil droplets in the solution that are not emulsified. Preferably, the above steps are performed when the degreasing solution is in use.

[0035] Step 2: Extract the unemulsified floating oil from the oil collection area. Similarly, this step can also be performed when the degreasing solution is used.

[0036] The floating oil skimmer 3 can continuously transport floating oil to the oil collection area during oil removal. When the connecting portion 206 overlaps with the gate 203, the oil collection area contains emulsified oil, oil removal solution and floating oil, while the oil removal area contains only emulsified oil and oil removal solution. The density of emulsified oil and oil removal solution is similar to that of water, while the density of floating oil is lower than that of water. Therefore, when the oil collection area and the oil removal area are connected, the oil collection area has a higher liquid level than the oil removal area because the upper layer is floating oil.

[0037] Preferably, Figure 6 As shown, two floating oil skimmers 3 are connected by a square frame 8. The square frame 8 is also provided with a bracket 10 for supporting a second hose 9. The bracket 10 moves with the floating oil skimmer 3, and at the same time, the second hose 9 on the bracket 10 moves up and down with the floating oil skimmer 3. The relative height of the liquid inlet of the second hose 9 is greater than the relative height of the liquid inlet of the floating oil skimmer 3.

[0038] Step 3: Extract the wastewater containing the emulsified oil from the degreasing tank and break the emulsion. It should be noted that before extracting the liquid containing the emulsified oil from the degreasing tank, use the flotation unit 7 to reduce the dispersed oil droplets in the wastewater that are not emulsified as much as possible; Step 4: Add a pH regulator to the wastewater after demulsification to lower the pH value of the wastewater. The pH regulator is 10% sulfuric acid, which is used to neutralize the alkaline substances in the wastewater. The pH value of the wastewater is between 6 and 8. Step 5, adding a flocculant and stirring, and obtaining a treated liquid after separation; Step six: Use ultrafiltration membrane / reverse osmosis membrane to filter the treated liquid to obtain qualified water. The wastewater after preliminary treatment such as flocculation, sedimentation or flotation is filtered through ultrafiltration membrane or reverse osmosis membrane.

[0039] Ultrafiltration membranes have larger pore sizes and can remove suspended particles, some dissolved matter, and organic matter from water, allowing wastewater to meet discharge standards. The reverse osmosis membrane has a smaller pore size and needs to be pressurized to allow the treated liquid to pass through. The resulting qualified water can be recycled; In addition, the ultrafiltration membrane and the reverse osmosis membrane can also be combined so that the treated liquid first passes through the ultrafiltration membrane and then passes through the reverse osmosis membrane to obtain qualified water, thereby increasing the service life of the reverse osmosis membrane.

[0040] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0041] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0042] The present invention and its embodiments are described above. This description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A process for treating electroplating pretreatment wastewater, characterized in that: The following steps are involved: Step 1: Use an oil removal tank to store the floating oil in the oil collection area, and increase the floating oil content on the liquid surface of the oil collection area; Step 2: Extract the unemulsified floating oil in the oil collection area; Step 3: extract the wastewater containing emulsified oil from the degreasing tank and perform demulsification treatment; Step 4: Add a pH regulator to the wastewater after demulsification to reduce the pH value of the wastewater to 6-8; Step 5: Add flocculant, stir and separate to obtain treated liquid; Step 6: Filter the treated liquid to obtain qualified water.

2. A process for treating electroplating pretreatment wastewater according to claim 1, characterized in that: The oil removal tank includes an oil removal area and an oil collection area. The liquid levels of the oil removal area and the oil collection area are not interconnected, and the liquid level of the oil removal area is continuously input into the oil collection area.

3. A process for treating electroplating pretreatment wastewater according to claim 2, characterized in that: Steps 1 and 2 are carried out in a deoiled state.

4. The electroplating pretreatment wastewater treatment process according to claim 1, characterized in that: In step 1, the unemulsified dispersed oil in the solution is floated by air flotation.

5. The electroplating pretreatment wastewater treatment process according to claim 1, characterized in that: When filtering the treated liquid in step six, it is first filtered through an ultrafiltration membrane and then filtered through a reverse osmosis membrane.

6. A degreasing tank used in the electroplating pretreatment wastewater treatment process according to any one of claims 1 to 5, characterized in that: The deoiling tank is provided with a plurality of floating deoilers which continuously input the liquid level in the deoiling area into the oil collecting area. The floating deoilers are connected by a square frame. A bracket is provided on the square frame. The bracket moves with the floating deoiler and enables the second hose on the bracket to move up and down with the floating deoiler.

7. The degreasing tank according to claim 4, characterized in that: The relative height of the liquid inlet of the second hose is greater than the relative height of the liquid inlet of the floating oil remover.

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